When an iPhone or iPad is connected to an Apple iPad Dock Connector to VGA Adapter, apps are able to access a second screen. If the connector is attached to a display device, such as a monitor or a projector, it is possible for an app to display content on that device.
A reasonable expectation might be that whatever is being displayed on the device's primary screen will also shown on the display that is connected via the VGA-out adapter. But this is not the case, rather each app needs to specifically tell the second screen what to display. Because the second screen is almost certainly a different size and shape to the device screen, displaying the same content would not be an ideal solution anyway. Most available apps do not make use of the second screen, and so the VGA output will be blank except when running an app which is designed to use the second screen.
Since version 1.1.1, MMDS for iOS will automatically make use of the VGA output device. The second screen shows the same content as the device screen, with some differences:
Note that the VGA-out adapter only works with the iPad and iPhone/iPod devices of 4th-generation or later. If in doubt, check with Apple before purchasing the adapter for your device.
When MMDS opens, the main view consists of a number of sections, one for each available datasheet. The display on the second screen is analogous:
As you can see, the second screen shows the same content, but fitted to a different size, and without the extra decorations that allow interaction.
The main view on the device can be scrolled up and down by swiping your finger. Scrolling the main view on the device does not cause the analogous view on the second screen to be scrolled. The second screen stays still.
To update the second screen to show the same part of the content, it is necessary to pick a datasheet, touch the banner, and hold it for a fraction of a second, e.g. the Functional Groups template datasheet:
The banner will highlight briefly, then the second screen will be scrolled so that the selected datasheet is moved to the centre:
The two screens are not tightly coupled for a good reason: this makes it possible for the operator of the device to scroll around, looking for particular content. Anybody who is watching the VGA-output screen will not have to watch the screen flickering up and down. If the operator decides to show a different part of the data collection, the touch-and-hold method is a convenient way of ensuring that both displays are in sync.
When individual molecules are selected within a datasheet, the second display is also updated:
DataSheet Detail View
The detail view for a datasheet is mirrored in a very similar way to the main menu. The scrolling position of the second display is only updated when a row is selected.
The button bank menus and decorations and are not shown on the second display, because it is not interactive.
Molecule Editor View
When editing a molecular structure, the second display is updated to show the current structure at all times, as well as the selection state and current atom or bond. All other decorations, such as the button banks, context bank, crayon, traversal indicators etc. are omitted for clarity:
The structure view shown on the second screen is at all times scaled and centred in order to show the structure onscreen. This is because the display device on the other end of the VGA-adapter is typically much larger than the iPhone or iPad device, and is almost always large enough to accommodate the whole structure. And because it is not interactive, there is no need to show it being zoomed in during the editing process:
MMDS uses the secondary screen provided by a VGA adapter to display a mirrored version of its content. The mirrored output fits the output device size, leaves out the interactive display elements, and is designed to reduce the amount of visual jitter. This makes MMDS a useful tool for impromptu presentations and collaborative design sessions, such as project group meetings.